An AC-type plasma display panel (hereafter abbreviated to PDP) is a type of gas discharge panel, well-known in the art as one example of a display panel.
A PDP is illustrated in FIG. 42. Here, the PDP is constructed from a front substrate 2000 and a back substrate 2100. The front substrate 2000 is generally produced by forming discharge electrodes 2002 upon a front glass plate 2101. This structure is then covered with a dielectric glass layer 2003 and a protective layer of magnesium oxide (MgO) 2004.
The back substrate 2100 is formed by arranging address electrodes 2102, barrier ribs 2103 and a phosphor layer 2104 on a back glass plate 2101. The front substrate 2000 and the back substrate 2001 are then fixed together, and discharge spaces 2200 are formed by introducing a discharge gas into the spaces demarcated by the barrier ribs 2103. Cells are formed in the discharge spaces 2200 at the points where discharge electrodes 2002 and address electrodes 2102 intersect. FIG. 42 shows only one such cell, but in fact the PDP normally includes a plurality of cells in which the phosphor layer 2104 is composed of alternating red, green and blue phosphors, enabling a color display to be produced. Note that in the drawing, the discharge electrodes 2002 and the address electrodes 2102 are drawn as if arranged in parallel, but in fact they are arranged at right angles.
A discharge gas, such as a mixture of neon and xenon, is normally enclosed into the discharge spaces 2200 at a pressure of around 500 Torr (6.65×104 Pa).
In practice, however, such conventional PDPs have not always been able to achieve satisfactory luminance. In order to improve luminance, it is considered necessary to enclose the discharge gas inside the discharge spaces 2200 at an internal pressure exceeding 500 Torr (6.65×104 Pa).
However, with the internal pressure in the discharge spaces 2200 is raised to 760 Torr (1.01×105 Pa) or 1000 Torr (1.33×105 Pa), for example, gaps are generated between the barrier ribs 2103 formed on the back glass plate 2101 and the front substrate 2000, while the front and back substrates 2000 and 2100 bulge outwards. This means that neighboring discharge spaces 2200 are no longer effectively divided by the barrier ribs 2103, causing the display performance of the PDP to deteriorate.
Even if the internal pressure is set at 760 Torr (1 .01×105 Pa) or less, the barrier ribs 2103 are not connected to the front substrate 2100, so that external vibrations or vibrations caused by driving the PDP itself bring the barrier ribs 2103 and the front substrate 2000 repeatedly into contact, generating noise.
In order to correct these problems, one related technique has proposed that the topmost edge of the barrier ribs 2103 be coated with a bonding agent before fixing the pair of substrates together to form the discharge spaces 2200. A gas discharge panel in which gas has been sealed at a higher pressure is produced, realizing an improvement in luminance. Such a procedure is described in Japanese Patent Application No. 9-49006.
However, when a well-known method such as screen-printing is used to apply the bonding agent to the topmost edge of the barrier ribs 2103, it is difficult to apply the bonding agent equally to the very long and narrow top surfaces of the barrier ribs 2103 without leaving some parts uncovered. In the case of screen-printing, matching an aperture pattern accurately to the shape of the barrier ribs 2103 has proved extremely difficult. As a result, finding a simple method for improving bonding strength, while maintaining display performance and preventing the generation of distortion when the barrier ribs 2103 touch the front substrate 2000 has posed considerable obstacles.
Furthermore, the properties of the dielectric glass layer 2003 covering the electrodes change if exposed to the discharge spaces 2200. As a result, a protective coat of MgO or similar is usually formed to cover the surface of the dielectric glass layer 2003, as described above. Even if a protective layer 2004 is applied in this way, however, the tops of the barrier ribs 2103 are connected after the protective layer 2004 has been applied, and so the surfaces of the bonding agent are not covered by the protective layer 2004. Thus, the properties of the surface of the bonding agent change as a result of exposure to the discharge spaces 2200. Substances produced by this change pollute the discharge spaces 2200 and are the cause of such problems as rises in discharge voltage, falls in discharge efficiency and deterioration in the phosphors.